Sidelink relay, authorized as an independent work item in both 3GPP R17 and R18, is a promising technology for facilitating future V2X communication in 5G New Radio (NR). As specified by 3GPP, several important factors of NR sidelink, including flexible hop-by-hop operation mode selection, sidelink path loss based power control, and resource sharing with uplink communications, were partially (if not totally) ignored in available studies. In light of this, we propose a general multi-hop NR sidelink relay scheme, namely, NSR- $(\rho,\omega,m)$ , for flexible dissemination of a typical Decentralized Environmental Notification Message (DENM). To efficiently characterize the multi-hop DENM dissemination process under NSR- $(\rho,\omega,m)$ , we further develop a stochastic geometry-based theoretical framework, by carefully taking into account the above 3GPP specified important factors. With the help of the theoretical framework, we are able to derive the end-to-end delivery probability and the total dissemination distance of a given DENM. Extensive numerical results are presented to verify the effectiveness of the theoretical framework. For a given DENM with a limited lifetime, it is also proved that the NSR- $(\rho,\omega,m)$ scheme is of great potential in significantly expanding the achievable performance region, by properly tuning the parameters $\rho$ , $\omega$ , and $m$ .